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ULY CLINIC
ULY CLINIC
24 Septemba 2025, 07:25:24
Fränkel’s sign
Fränkel’s sign refers to excessive range of passive motion at the hip joint observed in patients with tabes dorsalis. The increased motion results from decreased muscle tone in the muscles surrounding the hip, reflecting impaired proprioceptive input from the dorsal columns of the spinal cord.
Pathophysiology
Tabes dorsalis, a late manifestation of neurosyphilis, involves degeneration of the dorsal columns and dorsal roots.
Loss of proprioceptive input reduces muscle tone and reflex stabilization around joints.
The hip joint is particularly affected, resulting in hypermobile or “floppy” movements during passive examination.
Examination Technique
Patient positioning: Place the patient in a supine position.
Passive hip assessment: Gently move the hip through flexion, extension, abduction, and adduction.
Observation: Note range of motion, resistance, and joint stability.
Documentation: Compare both sides and record any asymmetry or excessive mobility.
Clinical Features
Feature | Manifestation |
Hip mobility | Increased passive range of motion |
Muscle tone | Decreased in surrounding hip muscles |
Gait abnormalities | Wide-based or unsteady gait due to proprioceptive loss |
Associated neurologic signs | Argyll Robertson pupils, sensory ataxia, lightning pains |
Differential Diagnosis
Condition | Key Feature | Notes |
Tabes dorsalis | Excessive passive joint motion + dorsal column signs | Late manifestation of untreated syphilis |
Peripheral neuropathy | Weakness and decreased tone | Usually distal, not joint-specific |
Cerebellar ataxia | Coordination deficits, but normal passive tone | Gait unsteady, joint mobility normal |
Myopathy | Generalized hypotonia | Muscle weakness more pronounced than hypermobility |
Ligamentous laxity / Ehlers-Danlos syndrome | Hypermobile joints | Congenital connective tissue disorder |
Pediatric considerations
Rare, as tabes dorsalis is extremely uncommon in children.
Congenital neuromuscular disorders may cause joint hypermobility that mimics Fränkel’s sign.
Geriatric Considerations
Elderly patients may present with late-onset syphilitic neuropathy.
Joint hypermobility may increase risk of falls and hip instability.
Limitations
Hypermobility may be subtle in early stages.
Must distinguish from congenital joint laxity or other neuromuscular disorders.
Patient counseling
Explain that excessive joint mobility reflects nerve dysfunction rather than a primary joint problem.
Emphasize the importance of evaluation and treatment for underlying syphilis.
Advise on fall prevention, physical therapy, and supportive care to maintain stability.
Conclusion
Fränkel’s sign is an indicator of hip joint hypermobility due to decreased muscle tone in tabes dorsalis, a form of late neurosyphilis. Careful neurological and musculoskeletal assessment can aid in diagnosis, guide treatment, and prevent complications such as falls and joint injury.
References
Ghanem KG. Neurosyphilis: A historical perspective and review. Curr Opin Infect Dis. 2010;23(1):21–27.
Parikh S, et al. Clinical neurology and examination of reflexes in syphilitic neuropathy. Neurol Clin. 2013;31(2):501–517.
Ropper AH, Samuels MA. Adams and Victor’s Principles of Neurology. 11th ed. New York: McGraw-Hill; 2021.
Centers for Disease Control and Prevention (CDC). Syphilis – CDC Fact Sheet. 2022.